The publication “Dynamic Avalanche in Diodes with Local Lifetime Control by Means of Palladium” (Microelectronics Journal 39, 878-883) describes a known diode, in which a homogeneous, continuous layer with Palladium and Palladium related defects can be introduced into the diode by radiation enhanced diffusion (RED) in order to convert the lightly doped n-base layer close to the anode junction of the diode to a lightly doped p-layer. Thereby, the breakdown voltage of the device can be improved because the peak electric field can be reduced. For the same reason, the dynamic avalanche during fast recovery can be postponed to higher voltages and more robust devices can be obtained. At the same time, the carrier lifetime may be decreased with a small increase of the leakage current. Such Palladium layers may only be applied as continuous layers over the whole plane of the diode. However, in many applications it may not be desired to have such a layer over the whole plane. For example, this may be the case of chip diodes with a planar junction termination in which this p-layer may not be present. In such cases it can be advantageous to include selectively processed p-layers only at the places where their effect may be beneficial. In general, this process can be advantages to any device with a blocking junction, in which increased avalanche ruggedness is needed.
Also the publication IEEE Transactions on Electron Devices, Vol. 54 (2007), 1521-1526 describes a method, in which a continuous Palladium layer can be created. In order to create the Pd layer, the anode side of a wafer can be sputtered with Palladium. Then, the anode side can be irradiated with alpha particles giving a defect peak in a depth of about 70 μm. Afterwards the device can be annealed at a temperature below 700° C. so that the Palladium particles diffuses into the wafer to the defect places.
Another application can be in compensation type devices, where the p-type columns coming from a surface or shallow p-type well into a certain depth of the silicon n-type wafer may be needed. The p-columns can be positioned in a way that they finally alternate n-type columns of a similar size. The n-columns are actually the remaining parts of the n-type substrate which are not changed to that of the p-type. This way, the spatial distribution of the electric field can be completely flat by virtue of the field compensation effect between the n- and p-columns and the breakdown voltage of a component can be high even for a relatively high doping level of the columns. Known methods of processing of such columns may be performed in several steps using rather complex processing.
In DE 40 26 797 A1, the creation of recombination centers is described. The charge carrier lifetime can be adjusted by creating defects by proton irradiation and then diffusing gold or Platinum onto a wafer. The particle irradiation can be performed through a mask, thereby creating a lateral profile. The diffusion in case of gold can be performed at 550 to 800° C. By the described method, the Platinum or gold particles are used to create defect centers. No doping is created by the diffused particles.